How can you tell the size of a bicycle?

13 December 2023

This image came to mind today from when we used to watch cartoons as children.

The typical big, strapping character who pedaled completely cramped because he was on a tiny bike.

It’s comical, but it happens more than you would imagine in real life.

And also the other way around.

Small people for whom riding a bike is an ordeal because they can’t reach the pedals.

Using your bike to get around is cool, but you have to choose your size wisely.

In this itinerary we will see:

  • Why it is important to choose the right size to avoid injuries.
  • What bike sizes are available (it’s as easy as clothes).
  • How to make the right choice to feel like you’re pedaling on cotton.

Let’s roll!

Why you should choose the best bike size if you want to ride comfortably

If you don’t ride your bike much, you might think:

“For once, I don’t think size matters.”


These can be some of the consequences of not getting the size of your bike right:

  • If it’s too big for you, you won’t reach the pedals comfortably and you’ll be exhausted before you’ve gone half a meter.
  • If it is too small, you may slouch and feel uncomfortable during the whole ride.

Well, you’ll be looking forward to the end of the route and won’t enjoy it.

But there is something even more important: you can injure yourself by having a bad posture (especially your back, neck and knees).

Although you may think that it is not very difficult to get injured because it will be a short ride, the reality is that in the first few minutes you can get hurt quite badly.

Take our advice and choose your bike size wisely.

Two people pedaling on bicycles of different sizes

What bike sizes exist: complete guide and sizing chart

Bike sizes are like clothing sizes: you have to choose the one that fits you best.

There is something they both share that we are not too happy about, and that is that not all manufacturers use the same system.

Some use a numerical system (no, looking in the cupboard won’t help you in this case). Fortunately, most use the same method as the textile industry: XXS, XS, S, M, L, XL, and XXL.

Anything else you should know?

Yes, look closely:

  1. The size of a bike corresponds to the length of the vertical tube that connects the bottom bracket (pedals) to the seat post (not including the seat post, which can be raised and lowered independently of the size).
  2. The size of road bicycles is usually given in centimeters.
  3. Mountain bikes are usually measured in inches (1 inch = 2.54 centimeters).

Is there a table to be clear about it?

Yes, and we bring it to you below.

Bicycle sizing chart: all the information in a nutshell for our cyclocompanions

Sometimes it’s nice to have all the information collected and clear in a table.

Keep an eye on it.

Bicycle size chart

Let’s get down to the most important thing: how to choose the right size for your bike.

How to choose the size of your bike to pedal at ease and avoid injury

The secret to calculating your ideal bike size lies in your inseam height (i.e. the distance between your groin and the ground).

Write down this measurement, we will now show you a formula to find your size. You don’t need to be a math whiz, just have a calculator handy.

Here we go.Woman holding a bicycle by the saddle for size calculation

#1 Formula for calculating your mountain bike size

If you are going to ride a mountain bike, apply this formula to calculate the size:

Inseam height multiplied by 0.21.

Let’s see an example: let’s imagine that your inseam height is 85 centimeters.

85 x 0,21 = 17,85.

That is, rounding up, your size is 18 inches (size M according to the chart we have shared with you above).

#2 Formula for calculating your road bike size

The formula is very similar to the previous one.

On this occasion, you must multiply the inseam height by 0.65.

Let’s calculate an example again, with a person who has a crotch height of 85 centimeters.

85 x 0,65 = 55,25.

Your size is 55 centimeters (corresponding to M).

What if you are between two sizes according to the formula?

If your result is just between two sizes, we usually recommend the smaller size.

However, we encourage you to test ride both bikes whenever you can to see which one you feel more comfortable on.

The reason?

In addition to the crotch height, more averages have an influence. For example, your height or the length of your torso.

What to do after choosing your bike size

After choosing the size of your bike you just need to find the route and enjoy.

If you like to make things easier for yourself, on our website we have routes and itineraries of 1, 2 and more days by city, road and mountain (and for all levels, including families).

Choose the one that best suits you and enjoy how cool it is to ride on two wheels.

Hit the pedals and discover Madrid!


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